Solid bolsters cut from resilient foam have been used for many years to assist in relieving lower back pain. Such bolsters are available in a variety of shapes and sizes. They are typically sold as generic products in foam shops. Such bolsters have solid trapezoidal configuration that includes upwardly-inclined surface areas exposed across the top of the bolster and intersecting one another at a right angle. One of these areas intersects the base of the bolster at an acute angle and obtuse for engagement by the legs.
One difficulty with foam bolsters is the inherent bulk of material required to support the legs of a user. Such bolsters cannot be easily carried or shipped from one location to another. In addition, the foam material must be relatively stiff in order to provide the required support for the weight of the user's legs. The foam material will not be compressed uniformly about the leg surfaces engaging the bolster, which eventually interferes with circulation of blood through the legs during its use. In addition, foam bolsters must be provided in several sizes so as to meet the dimensional requirements of various users.
Another prior product designed for such leg support is known as the "Waverly Wedge." It comprises a planar inflatable member having transverse tubes and bendable along a transverse line to form inclined areas defined by tension straps extending between the respective ends of the device. This structure requires rather substantial interior air pressure in order to be self-supporting over the spaced straps. It lacks lateral stability and, if not properly inflated, will not attain the proper upright configuration for use as a leg support.
The present invention was designed to provide a portable bolster that can be readily packed in luggage for travel purposes and which does not require substantial storage or closet space in the home when it is not in use. As a result of this development effort, it was discovered that the inflatable product could be adapted to the dimensional needs of a wide range of people, while maintaining both upright and lateral stability for support purposes. This stability is provided by a unique combination of horizontal and upright ribbing members within the bolster.